A Greek yogurt or Greek style yogurt is a type of yogurt in which serum from the yogurt has been extracted. The Greek style yogurt is high in protein, and has a tangier, less sweet as well as creamier taste than a regular yogurt. For these reasons, it has become increasingly popular and is now a $2 billion a year industry.
Production of the Greek style yogurt, however, produces a large quantity of the serum as a waste product. For example, it takes about four pounds of milk to make one pound of the yogurt. The other three pounds are extracted out of the yogurt as thin acidic serum.
A typical composition of the serum extracted from the Greek style yogurt includes total solids by weight of about 5.1% to about 5.4%: primarily lactose (3.95% to 4.20%), protein (0.25% to 0.28%), fat (0%), lactic acid (0.32% to 0.35%) and ash (0.60% to 0.65%). Due to the serum having fewer solids and being more acidic than other milk serums, the serum from the Greek style yogurt is difficult to process, especially in crystallizing and drying the serum. Moreover, the perishable nature of the serum and the lack of research and investigation in its processing methods have resulted in a negligible utilization of the serum and the inability of entering the food chain.
In the past, the yogurt makers gave away the serum as a feed additive to local farmers and even paid them to take it. However, due to the exploding popularity of the Greek style yogurt, the amount of serum being produced as a by-product has overgrown the capacity of the farmers to use it. Moreover, the serum cannot be simply thrown away as it would rob oxygen from streams and rivers, destroying aquatic life over potentially large areas.
Not surprisingly, in Greece, the utilization of the yogurt serum derived from the Greek style yogurt production has become a highly important environmental issue. For that reason, the processing of the Greek style strained yogurt serum became last year's subject of research and investigation to look for better ways to use the by-product.
However, past attempts to process the serum derived from the Greek style yogurt into a powder form have only resulted in the production of hygroscopic powder with high degree of caking. Additionally, that powder was discolored and was characterized by salty flavor with the absence of the typical yogurt flavor.
Therefore, it would be desirable to provide a system and method for manufacturing a powder from the Greek style strained yogurt serum which is non-hygroscopic, less likely to form lumps in storage, which retains the initial characteristics of the serum including high nutritional value and the typical flavor of the Greek style strained yogurt, and which is of sufficiently high quality to be fit for human consumption.